(Fluorinated phenoxy)(3-perfluoroalkylphenoxy)-cyclic phosphazenes

ABSTRACT

Cyclic phosphazenes completely substituted with fluorinated phenoxy and m-perfluoroalkylphenoxy moieties in ratios ranging from about 1:1 to about 1:5 are disclosed. These compounds, either alone or as additives, are useful as high temperature lubricants.

BACKGROUND OF THE INVENTION

The present invention is related to cyclic phosphazenes.

Various phosphazenes are known in the art. For example, U.S. Pat. Nos.3,316,330 and 3,234,304 disclose cyclic compounds corresponding to theformula:

    P.sub.m N.sub.m R.sub.x R'.sub.y R".sub.z                  (I)

wherein R is m-trifluoromethoxyphenoxy, R' is phenoxy and R" ism-trifluoromethylphenoxy, m is an integer of from 3 to 7, x is at leastone and the sum of x, y and z is 2m. The materials are disclosed to beuseful as high temperature lubricants, working fluids and plasticizers.Additional examples of other substituted phosphazenes are disclosed inU.S. Pat. No. 3,136,727; European Patent Application 0241877; U.S. Pat.No. 3,280,222 and U.S. Pat. No. 3,459,838. These phosphazenes are alsogenerally taught to be useful as lubricants and working fluids.

The demands placed on these materials and other existing lubricants arecurrently undergoing significant changes. Engines are being developedfor automotive and aeronautic applications that have requirementsdramatically different from those of engines currently in use. It isanticipated that these engines will operate at temperatures exceeding250° C. and will be constructed using materials new or different fromthose currently in use. Thus, what is needed are novel compounds usefulas lubricants or lubricant additives that are stable at the high usetemperatures while possessing the other properties required oflubricants.

SUMMARY OF THE INVENTION

The present invention is directed to oligomeric, preferably trimeric ortetrameric or mixtures thereof, cyclic phosphazenes substituted withfluorinated phenoxy moieties and 3-perfluoroalkylphenoxy moieties withthe proviso that the ratio of fluorinated phenoxy to3-perfluoroalkylphenoxy moieties on the phosphazene ring ranges fromabout 1:5 to about 1:1.

The invention is further directed to lubricant compositions comprisingone or more of the above-described phosphazenes.

The compounds and compositions of the present invention are useful asextended temperature lubricants.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS

The cyclic phosphazenes of the present invention are preferably trimericalthough higher oligomers such as tetramers may be used. When thetrimeric oligomers are used, they may contain minor amounts of highers.

The cyclic phosphazenes preferably correspond to the formula: ##STR1##wherein n is 3 through 7, R is individually in each occurrencefluorinated phenoxy or 3-perfluoroalkylphenoxy with the proviso that theratio of fluorinated phenoxy to 3-perfluoroalkylphenoxy ranges fromabout 1:5 to about 1:1.

The fluorinated phenoxy moieties contain from one to five fluorineatoms. It is preferred that the fluorinated phenoxy moiety contain onefluorine atom and that the fluorine atom is meta or para to the oxygenatom of the phenoxy moiety. The perfluoroalkyl group of themeta-perfluoroalkylphenoxy is preferably a lower perfluoroalkyl grouphaving from one to about five carbon atoms and is most preferably atrifluoromethyl group.

The ratio of fluorinated phenoxy to perfluoroalkylphenoxy substituentsranges from about 1:5 to about 1:1. It is preferred that the ratioranges from about 1:2 to about 1:1. It is more preferred that the ratiois about 1:2. While the compounds of the present invention are describedas single molecules having specified substituents present in a statedratio, it will be realized by one skilled in the art that the compoundswill exist as statistical mixtures of molecules. Some of these moleculeswill have the specified ratio of substituents while others will havehigher or lower ratios. However, the phosphazenes will, within thesestatistical mixtures, have substituents present at the specified ratios.

Non-limiting examples of the cyclic phosphazenes of this invention thusinclude2,2,4,4,6,6-di(4-fluorophenoxy)tetra(3-trifluoromethylphenoxy)-1,3,5-triaza-2,4,6-triphosphorine,2,2,4,4,6,6-di(3-fluorophenoxy)tetra(3-trifluoromethylphenoxy)-1,3,5-triaza-2,4,6-triphosphorine,2,2,4,4,6,6-di(2-fluorophenoxy)tetra(3-trifluoromethylphenoxy)-1,3,5-triaza-2,4,6-triphosphorine,2,2,4,4,6,6-tri(2-fluorophenoxy)tri(3-trifluoromethylphenoxy)-1,3,5-triaza-2,4,6-triphosphorine,2,2,4,4,6,6-tri(3-fluorophenoxy)tri(3-trifluoromethylphenoxy)-1,3,5-triaza-2,4,6-triphosphorine,2,2,4,4,6,6-tri(4-fluorophenoxy)tri(3-trifluoromethylphenoxy)-1,3,5-triaza-2,4,6-triphosphorine,2,2,4,4,6,6,8,8-tri(4-fluorophenoxy)penta(3-trifluoromethylphenoxy)-1,3,5,7-tetraza-2,4,6,8-tetraphosphorine,2,2,4,4,6,6,8,8-tri(3-fluorophenoxy)penta(3-trifluoromethylphenoxy)-1,3,5,7-tetraza-2,4,6,8-tetraphosphorine,2,2,4,4,6,6,8,8-tetra(4-fluorophenoxy)tetra(3-trifluoromethylphenoxy)-1,3,5,7-tetraza-2,4,6,8-tetraphosphorine,2,2,4,4,6,6,8,8-tetra(3-fluorophenoxy)tetra(3-trifluoromethylphenoxy)-1,3,5,7-tetraza-2,4,6,8-tetraphosphorine,2,2,4,4,6,6,8,8-2.57(3-fluorophenoxy)-5.43(3-trifluoromethylphenoxy)-1,3,5,7-tetraza-2,4,6,8-tetraphosphorine,2,2,4,4,6,6,8,8-2.57(4-fluorophenoxy)-5.43(3-trifluoromethylphenoxy)-1,3,5,7-tetraza-2,4,6,8-tetraphosphorineand mixtures thereof. In a preferred embodiment, the phosphazene is2,2,4,4,6,6-di(3-fluorophenoxy)tetra(m-trifluoromethylphenoxy)-1,3,5-triaza-2,4,6-triphosphorine,2,2,4,4,6,6-di(4-fluorophenoxy)tetra(m-trifluoromethylphenoxy)-1,3,5,-triaza-2,4,6-triphosphorineor mixtures thereof.

The compounds of this invention may be prepared by methods known in theart. It is preferred that they are prepared in a one-pot, two-stagereaction. In the first stage, a fluorinated phenol and aperfluoroalkylphenol are placed into a flask with a solvent. An alkalimetal hydroxide is added and the mixture is allowed to reflux and thewaters of reaction are removed. The mixture is then allowed to cool anda halogenated cyclic phosphazene is added and the mixture is refluxed.The product is then recovered using conventional techniques. Thefluorinated phenol, perfluoroalkylphenol and halogenated phosphazenestarting materials are commercially available or may be prepared usingconventional techniques.

In the preparation of the compounds of this invention, the fluorinatedphenol, the perfluoroalkylphenol and the halogenated phosphazenereactants are used in amounts sufficient to insure that the fluorinatedphenol and perfluoroalkylphenol are present in a ratio of from about 1:1to about 1:2 and the fluorinated phenol and perfluoroalkylphenolcompletely replace the halogens on the phosphazene ring. For example,when the phosphazene is a trimer such as2,2,4,4,6,6-hexachloro-1,3,5-triaza-2,4,6-triphosphorine, it ispreferred to use at least about two moles of fluorinated phenol and atleast about four moles of perfluoroalkylphenol per mole of2,2,4,4,6,6-hexachloro-1,3,5-triaza-2,4,6-triphosphorine. When thephosphazene is a tetramer, it is preferred to use at least about 2.6moles of fluorinated phenol and at least about 5.4 moles ofperfluoroalkylphenol per mole of2,2,4,4,6,6,8,8-octachloro-1,3,5,7-tetraza-2,4,6,8-tetraphosphorine. Itis preferred to use a slight stoichiometric excess each of fluorinatedphenol and perfluoroalkylphenol to insure complete reaction.

The compounds of this invention are useful as lubricants over extendedtemperature ranges. They may be used alone and also may be used inconjunction with various additives to improve their performance.Additionally, they may themselves be used as additives with other basestocks.

When used as an additive to a base stock, the phosphazenes of thepresent invention must be compatible with the base stock. By compatible,it is meant that the phosphazenes of the present invention may bereadily dispersed or dissolved in the base stock, either with or withoutthe addition of an appropriate surfactant. Examples of known lubricantbases useful in the compositions of this invention include organic oilsand greases well known to those skilled in the art. When thephosphazenes of the present invention are used as additives toconventional, compatible base stocks, it is preferred that the basestocks are polyglycols, polyphenyl ethers and polyol esters. It is morepreferred that the base stocks are polyphenyl ethers such as 5P4E whichis a polyphenyl ether having five phenyl groups and four ether linkages.Other preferred base stocks include polyol esters such aspentaerythritol tetra C₅₋₉ esters (PET).

The lubricant compositions of this invention comprise from about 0.1 toabout 100 weight percent of the phosphazenes of the invention. That is,the phosphazenes of this invention may be used as a lubricant base stock(i.e., lubricant composition is up to about 100 weight percentphosphazene) or they may be used as additives with other lubricants(i.e., lubricant composition contains at least about 0.1 weight percentphosphazene).

When the phosphazenes of this invention are used as lubricant additives,it is preferred that they are used in amounts of at least about 0.5weight percent, more preferably at least about 5 weight percent. It isalso preferred that the phosphazenes of the present invention, when usedas additives, are used in amounts of no greater than about 50 weightpercent, preferably no greater than about 20 weight percent.

As discussed above, the phosphazenes of the present invention may beused as lubricants themselves, either alone or with the addition ofadditives known in the art. When used as the lubricant base stock,additives useful in high temperature lubricants may be added. In thiscontext, it is preferred that the phosphazene of this invention compriseat least about 50 weight percent, more preferably at least about 95weight percent of the composition with one or more additives making upthe remainder of the lubricant composition. Additionally, thephosphazenes of this invention may be blended with other base stocks toprepare lubricants.

The following examples are provided for illustrative purposes only andshould not be construed as limiting the invention in any way. Unlessstated otherwise, all parts and percentages are by weight.

EXAMPLE 1 Preparation of2,2,4,4,6,6-di(4-fluorophenoxy)-tetra(3-trifluoromethylphenoxy)-1,3,5-triaza-2,4,6-triphosphorine

A 5.6-g (0.05 mole) portion of 4-fluorophenol and 16.2 g (0.1 mole)3-trifluoromethylphenol are placed into a flask with 100 ml of tolueneand 150 ml of xylene. The flask is equipped with a stirrer and aDean-Stark trap and 9.6 g (0.15) of potassium hydroxide are added. Themixture is stirred at reflux until waters of reaction cease to evolve.The mixture is then allowed to cool to 100° C. and 8.7 g (0.025 moles)of 2,2,4,4,6,6-hexachloro-1,3,5-triaza-2,4,6-triphosphazene are added inportions as a solid at such a rate to prevent the solvent fromdistilling from the flask. After this the mixture is refluxed for 16hours. After cooling, the product is stirred with 1 liter of dilute NaOHwater solution, separated and then stirred with 1 liter of water. Theproduct phase is separated, dried over sodium sulfate, filtered and lowboilers distilled and saved. The product,2,2,4,4,6,6-di(4-fluorophenoxy)-tetra(3-trifluoromethylphenoxy)-1,3,5-triaza-2,4,6-triphosphorine,is further distilled at 250° C. and 0.1 mm Hg to produce an oil with apour point at -10° C. and a thermal stability of 429° C. by DSC.

EXAMPLE 2

Following the procedure outlined in Example 1,2,2,4,4,6,6-di(2-fluorophenoxy)tetra(3-trifluoromethylphenoxy)-1,3,5-triaza-2,4,6-triphosphorine;2,2,4,4,6,6-di(3-fluorophenoxy)tetra(3-trifluoromethylphenoxy)-1,3,5-triaza-2,4,6-triphosphorine;2,2,4,4,6,6,8,8-2.57(4-fluorophenoxy)-5.43(3-trifluoromethylphenoxy)-1,3,5,7-tetraza-2,4,6,8-tetraphosphorine;and2,2,4,4,6,6,8,8-tri(4-fluorophenoxy)penta(3-trifluoromethylphenoxy)-1,3,5,7-tetraza-2,4,6,8-tetraphosphorineare prepared.

EXAMPLE 3 Preparation of mixture of 4/1 mole ratio of 2,2,4,4,6,6-di(2/1mole ratio of3-fluorophenoxy/4-fluorophenoxy)tetra(3-trifluoromethylphenoxy)-1,3,5-triaza-2,4,6-triphosphorineand 2,2,4,4,6,6,8,8-2.57(2/1 mole ratio of3-fluorophenoxy/4-fluorophenoxy)-5.43(3-trifluoromethylphenoxy)-1,3,5,7-tetraza-2,4,6,8-tetraphosphorine

A 26.3-g (0.23 mole) portion of a 2/1 mole ratio of3-fluorophenol/4-fluorophenol and 76 g (0.47 mole)3-trifluoromethylphenol are placed into a flask with 50 ml of diglymeand 500 ml of xylene. The flask is equipped with a stirrer and aDean-Stark trap and 46 g (0.7) of potassium hydroxide are added. Themixture is stirred at reflux until waters of reaction cease to evolve.The mixture is then allowed to cool to 100° C. and 27.8 g (0.02 moles)of 2,2,4,4,6,6-hexachloro-1,3,5-triaza-2,4,6-triphosphazene and 27.8 g(0.08) mole of2,2,4,4,6,6,8,8-octachloro-1,3,5,7-tetraza-2,4,6,8-tetraphosphazene areadded in portions as a solid at such a rate to prevent the solvent fromdistilling from the flask. After this the mixture is refluxed for 16hours. After cooling, the product is stirred with 1 liter of dilute NaOHwater solution, separated and then stirred with 1 liter of water. Theproduct phase is separated, dried over sodium sulfate, filtered and lowboilers distilled and saved. The product is distilled to produce an oilwith a pour point at -18° C. and boiling point of 285° C. at 0.5 mm Hg.

EXAMPLE 4 Friction and Wear Tests

The anti-wear and extreme pressure characteristics of the compounds andcompositions of this invention are measured using the four-ball testusing a Falex friction and wear tester. In this example, the compoundstested are trimeric cyclic phosphazenes, i.e.,1,3,5-triaza-2,4,6-triphosphorines having the substituents indicated inTable I below. The four-ball bearing balls used in this test are made ofAISI E-52100 steel. Test load is 45 Newtons (10 pounds). The test speedis 1200 rpm and each test is run for 1 hour unless noted otherwise.About 60 cubic centimeters of fluid are used for each test. Each test isconducted at 300° C. During each test, the torque as a function of thewear cycles is monitored on a real time data acquisition basis for dataanalysis to yield the coefficient of friction. Optical microscopepictures of the bearing balls are taken at the test completion and scardiameter is measured from these pictures. The data obtained is shown inTable I below.

                  TABLE I                                                         ______________________________________                                                                            Coeffi-                                                             Scar      cient                                           Substituted         Diameter  of                                        Run   Phosphazene         (mm)      Friction                                  ______________________________________                                        1     di(4-FPh)tetra(3-CF.sub.3 Ph).sup.1                                                               0.505     0.028                                     2     di(2-FPh)tetra(3-CF.sub.3 Ph).sup.1                                                               0.541     0.057                                     3     di(3-FPh)tetra(3-CF.sub.3 Ph).sup.1                                                               0.569     0.028                                     4     mono(3-FPh)penta(3-CF.sub.3 Ph).sup.1                                                             0.56      0.056                                     5     tri(3-FPh)tri(3-CF.sub.3 Ph).sup.1                                                                0.51      0.112                                     6.sup.2                                                                             hexa(3-CF.sub.3 Ph).sup.1                                                                         0.957     0.119                                     7.sup.2                                                                             hexa(Ph).sup.1      0.688     0.226                                     8.sup.2                                                                             di(3-ClPh)tetra(3-CF.sub.3 Ph).sup.1                                                              0.908     0.170                                     9.sup.2                                                                             di(Ph)tetra(3-CF.sub.3 Ph).sup.1                                                                  0.991     0.170                                     ______________________________________                                         .sup.1 FPh = fluorophenoxy                                                    CF.sub.3 Ph = trifluoromethylphenoxy                                          Ph = phenoxy                                                                  ClPh = chlorophenoxy                                                          .sup.2 Not an embodiment of the invention.                               

The data in the above table clearly demonstrates the effectiveness ofthe compounds of this invention as high temperature lubricants.

EXAMPLE 4

The procedure outlined in Example 3 is followed with the followingexceptions. The test load is 135 N and the phosphazenes used are bothtrimeric and tetrameric substituted phosphazenes. The results obtainedare shown in Table II below.

                  TABLE 11                                                        ______________________________________                                                      Scar Diameter                                                                             Coefficient                                         Phosphazene   (mm)        of Friction                                         ______________________________________                                        Trimer.sup.1  0.64        0.09                                                Tetramer.sup.2                                                                              0.70        0.10                                                ______________________________________                                         .sup.1                                                                        2,2,4,4,6,6di(4-fluorophenoxy)tetra-(3-trifluoromethylphenoxy)-1,3,5-tria    a-2,4,6-triphosphorine                                                         .sup.2                                                                        2,2,4,4,6,6,8,8tri(4-fluorophenoxy)penta-(3-trifluoromethylphenoxy)-1,3,5    7-tetraza-2,4,6,8-tetraphosphorine                                        

EXAMPLE 5 Additive Tests

The procedure outlined in Example 4 is followed with the exception thatthe phosphazene used in each case isdi(3-fluorophenoxy)tetra(3-trifluoromethylphenoxy)phosphazene. Further,the phosphazene is used with varying amounts of a polyphenyl ether(5P4E). In this test, the bearing balls used are M-50 steel balls andthe test is conducted at a load of 45 N (10 lb) and 135 N (30 lb). Thetest is conducted at 300° C. The results obtained are reported in TableIII below.

                  TABLE III                                                       ______________________________________                                        Concen-                                                                       tration    Load                                                               of         45 N           135 N                                                     Phospha- Scar     Coeffi- Scar   Coeffi-                                      zene     Diameter cient of                                                                              Diameter                                                                             cient of                               Run   (Wt %)   (mm)     Friction                                                                              (mm)   Friction                               ______________________________________                                        .sup. 1.sup.1                                                                       0        1.651    0.226   >2.8.sup.2                                                                           0.206                                  2     1        1.060    0.229   >1.74.sup.2                                                                          0.189                                  3     5        0.587    0.129   >1.76.sup.2                                                                          0.189                                  4     10       0.674    0.136   0.656  0.146                                  5     20       0.697    0.153   0.839  0.159                                  6     100      0.678    0.145   0.771  0.151                                  ______________________________________                                         .sup.1 Not an example of the invention.                                       .sup.2 Test stopped after 15 minutes of test run.                        

The data shown in Table III above demonstrates the effectiveness of thecompound of this invention as an additive to improve the properties ofknown lubricants.

EXAMPLE 6 Additive Tests

The procedure outlined in Example 5 is followed with the exception thatthe phosphazene used in each case istri(4-fluorophenoxy)tri(3-trifluoromethylphenoxy)phosphazene. Theconcentration of the phosphazene is 10 weight percent. At a load of 45N, the wear scar diameter is 0.82 mm and the coefficient of friction is0.158. At a load of 135 N, the wear scar diameter is 0.89 mm and thecoefficient of friction is 0.107.

EXAMPLE 7 Additive Test

The procedure outlined in Example 4 is followed with the exception thatthe phosphazene used in each case isdi(3-fluorophenoxy)tetra(3-trifluoromethylphenoxy)phosphazene. Further,the phosphazene is used with varying amounts of pentaerythritol tetraC₄₋₉ ester available commercially as Emery PET 2939. In this test, thebearing balls used are 52100 steel balls and the test is conducted at aload of 535 N (120 lb). The test is conducted at 200° C. The resultsobtained are reported in Table IV below.

                  TABLE IV                                                        ______________________________________                                        Percent      Scar Diameter                                                                             Coefficient                                          Triaza       (mm)        of Friction                                          ______________________________________                                         0           0.99        0.096                                                 1           0.43        0.056                                                 5           0.42        0.060                                                10           0.48        0.046                                                15           0.46        0.054                                                20           0.51        0.072                                                100          0.78        0.106                                                ______________________________________                                    

What is claimed is:
 1. A lubricant composition comprising a lubricantbase stock and from at least about 0.1 weight percent to no greater thanabout 50 weight percent of at least 1 cyclic phosphazene correspondingto the formula: ##STR2## wherein n is 3 through 7, R is individually ineach occurrence fluorinated phenoxy or 3-perfluoroalkylphenoxy with theproviso that the ratio of fluorinated phenoxy to 3-perfluoroalkylphenoxyranges from about 1:1 to about 1:5.
 2. The composition of claim 1wherein the ratio of fluorinated phenoxy to 3-perfluoroalkylphenoxy isabout 1:2.
 3. The composition of claim 1 wherein the lubricant basestock is a polyphenyl ether.
 4. The composition of claim 1 wherein thelubricant base stock is a pentaerythritol tetra C₅₋₉ ester.
 5. Thecomposition of claim 1 wherein the phosphazene comprises from 0.5 toabout 50 weight percent of the lubricant composition.
 6. The compositionof claim 5 wherein the phosphazene comprises from about 0.5 to about 20weight percent of the lubricant composition.
 7. The composition of claim6 wherein the phosphazene comprises from about 5 to about 20 weightpercent of the lubricant composition.
 8. The composition of claim 1wherein the phosphazene comprises2,2,4,4,6,6-di(4-fluorophenoxy)-tetra(3-trifluoromethylphenoxy)-1,3,5-triaza-2,4,6-triphosphorine,2,2,4,4,6,6-di(3-fluorophenoxy)-tetra(3-trifluoromethylphenoxy)-1,3,5-triaza-2,4,6-triphosphorine,2,2,4,4,6,6-di(2-fluorophenoxy)-tetra(3-trifluoromethylphenoxy)-1,3,5-triaza-2,4,6-triphosphorineand mixtures thereof.